Absorbent member comprising a water absorbing agent

Abstract

The present invention provides an absorbent member for use in absorbent articles, especially for use in diaper or training pants, the absorbent member comprising an absorbing agent which excels in water absorption properties. The absorbing agent is made by a method comprising a) a step of mixing a water absorbing resin, water, and a mixing aid without adding a water-soluble radical polymerization initiator and an ethylenically unsaturated monomer and b) a step of irradiating the resultant mixture with ultraviolet rays while keeping the mixture still agitating the mixture in order to maintain a mixed state.

1 . An absorbent member for use in absorbent articles, said absorbent member comprising an absorbing agent made by a method comprising the steps of 
 a) mixing a water absorbing resin, water, and a mixing aid without adding a water-soluble radical polymerization initiator and an ethylenically unsaturated monomer and    b) irradiating the resultant mixture with ultraviolet rays while still agitating the mixture in order to maintain a mixed state.    
   
   
       2 . An absorbent member according to  claim 1 , wherein in said method the amount of the water to be mixed is at least about 1 weight part and is less than about 50 weight parts based on about 100 weight parts of the water absorbing resin.  
   
   
       3 . An absorbent member according to  claim 1 , wherein in said method the mixing aid is at least one compound selected from the group consisting of surfactants, water-soluble polymer, hydrophilic organic solvents, water-soluble inorganic compounds, inorganic acid salts, organic acid salts.  
   
   
       4 . An absorbent member according to  claim 1 , wherein in said method the mixing aid is added in an amount of at least about 0.01 weight parts and less than about 50 weight parts, based on about 100 parts by weight of the water absorbent resin.  
   
   
       5 . An absorbent member according to  claim 1 , wherein in said method the mixing aid is mixed in the form of an aqueous solution with the water absorbing resin.  
   
   
       6 . An absorbent member according to  claim 5 , wherein in said method the aqueous solution has a surface tension of from about 40 dynes/cm to about 75 dynes/cm.  
   
   
       7 . An absorbent member according to  claim 3 , wherein in said method the surfactant is polyoxyethylene alkyl ether.  
   
   
       8 . An absorbent member according to  claim 3 , wherein in said method the surfactant is polyethylene glycol.  
   
   
       9 . An absorbent member according to  claim 3 , wherein in said method the water-soluble inorganic compound is a water-soluble metal salt.  
   
   
       10 . An absorbent member according to  claim 1 , wherein the water absorbing resin contains particles of a particle diameter of at least about 150 μm and less than about 850 μm in a ratio of from about 90 weight % to about 100 weight % of all the particles therein and has a weight average particle diameter (D50) of at least about 300 μm and less than about 500 μm and a logarithmic standard deviation (σζ) of particle distribution of from about 0.20 to about 0.45.  
   
   
       11 . An absorbent member according to  claim 1 , wherein the absorbency of physiological saline against pressure of about 2.07 kPa of the water absorbing agent is at least about 15 g/g and is less than about 50 g/g and is increased by at least about 1 g/g comparing with that of the water absorbing resin.  
   
   
       12 . An absorbent member according to  claim 1 , wherein in said method the water absorbent resin has an acid group and a neutralization degree (mol % of the neutralized acid group in the whole acid group) of from about 50 to about 95 mol %.  
   
   
       13 . An absorbent member according to  claim 1 , wherein the eluted soluble content of the water absorbing agent is at least about 0.1 weight parts and is less than about 30 weight parts, based on about 100 weight parts of the water absorbing resin.  
   
   
       14 . An absorbent member according to  claim 1 , wherein in said method the irradiation with the ultraviolet rays is carried out under increased temperatures.  
   
   
       15 . An absorbent member according to  claim 1 , wherein the water absorbing resin is obtained by polymerizing a monomer having acrylic acid (salt) as a main component thereof.  
   
   
       16 . An absorbent member according to  claim 1 , wherein the water absorbing resin is obtained by preparing a precursor water absorbing resin having a low neutralization ratio and mixing the precursor water absorbing resin with a base.